<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
  <ul>
    <li>我是列表项1</li>
    <li>我是列表项2</li>
    <li>我是列表项3</li>
  </ul>
  <script>
    // 父元素.removeChild(子元素);
    var ul = document.querySelector('ul');
    // 获取第二个li元素
    var li2 = ul.children[1];
    // 删除
    ul.removeChild(li2);

  </script>
</body>
</html>